Battery tester including flexible substrate and polyacetilynic material

ABSTRACT

A device for testing a battery, particularly a small, portable battery, comprising a flexible, transparent substrate on which is deposited a narrow band of a black light absorbing material. A conductive material, which may taper outwardly in opposite directions from a central point to a pair of outer terminals, is then deposited atop the substrate on the same side of the substrate as the absorber layer or on the opposite side of the substrate as the absorber layer. A layer of a cholesteric liquid crystal material is then deposited on the substrate on the opposite side from the black absorber layer or over the absorber layer. The conductive material is an epoxy cement-based conductor, preferably silver, printed or painted directly on to the substrate. An indicator scale is located along sections of the conductive material. To test a dry cell battery, the terminal ends of the conductive material are placed in contact with the battery terminals, causing a current to flow which heats the conductive material, the heat generated being the most intense at the central point and radiating outwardly. The heat is transferred through the thin substrate to the liquid crystal layer which results in a color change in the liquid crystal. The traverse of the color change along the length of the indicator scale, outwardly from the center point, is proportional to the current or voltage output or the condition of the battery to be tested and can be read on the indicator scale which is calibrated accordingly. The tester also includes means for determining the amp-hours or life of a battery.

RELATED APPLICATIONS

This is a continuation-in-part application of U.S. application Ser. No.723,329, filed Apr. 15, 1985.

BACKGROUND OF THE INVENTION

This invention relates to battery testers, particularly to an improvedtester for small, portable batteries, and more particularly to simplyconstructed, inexpensive tester with no moving parts, whereby a smallbattery can be readily tested.

The extent of the use of small batteries, particularly dry cellbatteries, has increased rapidly and steadily during the last decade,and a substantial effort has been directed to the production ofrecharging devices for such batteries, as well as providing means fortesting the strength or condition of the batteries. Batteries are oftenstored prior to use and in many instances are discarded for new oneswithout determining the existing strength or condition of the batteries,thereby resulting in a substantial waste of useful battery life.

A few battery testers and indicating devices are known in the prior artbut they are bulky, cumbersome or expensive, use complex electric orelectronic components and circuitry and are designed mostly for largelead-acid type batteries used in the powering of transmitters,receivers, servos and the like.

Some of these indicating devices or their components are exemplified inthe following patents:

U.S. Pat. No. 4,006,414 issued Feb. 1, 1977 to Robert Parker; U.S. Pat.No. 3,974,441 issued Aug. 10, 1976 to Johannes Van Den Haak; U.S. Pat.No. 4,022,706 issued May 10, 1977 to Frederick Davis; U.S. Pat. No.4,290,021 issued Sept. 15, 1981 to Jacob J. Thereon; U.S. Pat. No.4,066,897 issued Jan. 3, 1978 to Ralph L. Belcher; U.S. Pat. No.3,600,060 issued Aug. 17, 1971 to Donald Churchill; and U.S. Pat. No.4,360,780 issued Nov. 23, 1982 to William G. Skutch, Jr.

The foregoing status of the art indicates that a need has existed inthis field for an inexpensive and simple device or means for readilytesting the charge state or condition of batteries, such as those of the1.5 and 9 volt dry cell types. The battery tester described and claimedin the related application Ser. No. 723,329, has partially fulfilledthis need. with such a tester one could readily test batteriesespecially dry cell batteries before deciding to discard them andinstall new ones at the time of contemplated use. However, a need stillexists for an even more simply constructed dry cell battery tester aswell as a means to indicate the ampere-hours or the number of hours oramperage discharged or useful battery life remaining or for warrantypurposes on electrical appliances and equipment.

SUMMARY OF THE INVENTION

The present invention fills the above mentioned need by providing aneffective device for readily testing batteries such as the 1.5 and 9volt dry cell type and which, at the same time, lends itself to simpleand inexpensive means and methods of fabrication, as well as to providefor the determination of the amp-hours used up or the remainder ofuseful battery life.

Therefore, it is an object of the present invention to provide animproved means for testing batteries, particularly, dry cell batteries.

A further object of the invention is to provide a battery tester whichcan be readily used by purchasers of small, portable batteries and whichhas multiple voltage taps for testing batteries of different sizes anddifferent voltages.

Another object of the invention is to provide a battery tester whichbasically consists of a conductive material deposited in a specificpattern on a layer of a cholesteric crystal material carried on asubstrate, such that current flowing through the conductive materialproduces a temperature gradient, which in turn causes a color change ora line of delineation in the cholesteric liquid crystal material, thedistance traversed by the color change or the length of the line beingproportional to the strength of the battery.

Another object of the invention is to provide a method for fabricating abattery tester which includes depositing a cholesteric liquid crystalmaterial and a conductive material on a flexible substrate in selectedpatterns, such that contact of the battery terminals by opposite endportions of the conductive material results in a color change in theliquid crystal material which is an indication of the strength of thebattery.

Another object of the invention is to provide a method for making aplural pattern battery tester which utilizes a single layer of liquidcrystal material.

Another object is to provide a battery tester, such as the typedescribed and claimed in the above-referenced application Ser. No.723,329, which includes means for determining the amp-hrs of use left inthe battery.

Additional objects, advantages and novel features of the invention,together with additional features contributing thereto and advantagesaccruing therefrom will be apparent from the following description andthe accompanying illustrations of various embodiments of the inventionand the description of the fabrication technique therefor, as describedhereinafter. The objects and advantages of the invention may be realizedand attained by means of the instrumentalities and combinationsparticularly pointed out in the appended claims.

In accordance with the foregoing objects of the invention, the batterytester of this invention is similar to that in the application Ser. No.723,329, identified above, and basically consists of a flexible,preferably transparent substrate or film on which is deposited a layerof a dark, light absorbing material, and, on top of the absorber, alayer of a conductive material, such as silver, nickel or carbon in abinder base such as epoxy or urethane, in at least a single wedge or adouble wedge (bow-tie) configured pattern, and which terminates in orhas connected to the pattern, at least one pair of opposite ends orterminals for contacting the terminals of a battery, such as a dry cellbattery, to be tested. A microencapsulated cholesteric liquid crystallayer is deposited on the other side of the substrate.

By way of example, a thin film of a black, light absorbing or "backing"material is deposited on a thin, flexible, transparent substrate. Theblack backing material or absorber may be derived from any dark paintsuch as a black latex or uv curing paint. A conductive materialcomprising epoxy or urethane based silver, nickel or carbon granules orpowder is deposited on the transparent substrate or film on top of theabsorber layer, so as to form at least a single wedge or a "bow-tie"shaped pattern having terminal end portions. A layer of amicroencapsulated cholesteric liquid crystal material is then depositedon the other side of the substrate. When the terminal end portions ofthe conductive material are contacted with the terminals of a battery, acurrent through the conductive material, generating heat in theconductor. The heat is then transferred through the substrate to theliquid crystal material causing a change in its color. The color changein the liquid crystal material is rendered more readily visible ordiscernible by the black, light absorbing, backing material. To protectthe conductive pattern, a suitable protective coating may be depositedon all areas of at least the conductive pattern except the terminals orcontact points. The protective material may be any uv curing paint. Oneembodiment of the invention uses one bow-tie shaped pattern, with twosets of conductive patterns connected thereto, whereby either 1.5 or 9volt batteries may be conveniently tested using the same tester. Thetester may be used, for example, for testing a 9 volt battery, or aconventional 1.5 volt battery such as the cylindrical AAA, AA, C and Dtypes of batteries. But in addition, the tester may be provided with alayer of polyacetylene on one or a portion of one of the wedge shapedpatterns, which turns optically dark as function of time and temperatureto indicate amp-hrs, either used up or remaining in the battery, wherebythe battery life may be readily determined. A suitably calibrated scalemay be appended to the substrate to indicate the amp-hrs consumed.

Another embodiment of the subject invention utilizes multiple voltagetaps for use with batteries of different voltages and sizes.

When a current passes through the conductive material pattern, atemperature gradient is generated beginning at the center point of thedouble-wedge or "bow-tie" and radiates towards the terminal ends. Theheat generated is transferred through the substrate to the liquidcrystal material layer which changes color starting at a pointcorresponding to the central point of the bow-tie configuration of theconductor, moving farther towards the rounded edges of the bow-tiepattern. The farther the outward displacement of the color change, thegreater is the voltage output or the strength of the battery beingtested. A calibrated scale, indicating a relationship between voltage orcurrent vs. distance traveled, may be located along the bow-tie patternsuch that color changes in the liquid crystal material corresponding toonly the central section of the conductive material indicates a weakbattery while color changes in the liquid crystal material correspondingto a length beyond the central section and beyond or through the entirelength of the pattern indicates a good to a strong battery condition. Asthe liquid crystal layer is heated by current flow therethrough, thepolyacetylene material turns optically dark in proportion to theamp-hours in the battery being used up.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a bow-tie configured member of conductive material,with dimensions of the various sections thereof illustrated.

FIG. 2 illustrates an embodiment of the battery tester of theabove-referenced application Ser. No. 723,329.

FIG. 3 illustrates the battery tester of FIG. 2 positioned to test abattery having adjacent terminals such as a 1.5 volt battery.

FIG. 4 is an embodiment similar to that of FIG. 2 but utilizes only asingle conductive pattern having two sets of terminals and a singlelayer of liquid crystal material for testing batteries of differentvoltages.

FIG. 5 is an exploded view of the tester of FIG. 4.

FIG. 6 is an embodiment of a tester made in accordance with the subjectinvention which additionally incorporates means for determining theamp-hours of a battery being tested.

FIGS. 7 and 7A illustrate embodiments of a tester made in accordancewith the invention which includes a plurality of voltage taps wherebybatteries of different voltages can be tested with the same tester.

DETAILED DESCRIPTION OF THE INVENTION

The present invention involves an improved device for testing batteries,particularly dry cell batteries, and a method for fabricating oneembodiment of the device. One embodiment incorporates means fordetermining the life of a battery. For example, one embodiment can bereadily used to test batteries of the 9 volt type used in small portablecalculators, flashlights, portable stereos, travel clocks, portableradios and the like, which have two adjacent terminals or contactspoints on opposite ends of the battery. One embodiment incorporates avoltage tap for use with batteries of different voltages. Basically, thebattery tester of this invention is constructed in a manner similar tothat used in the construction of the tester described in theabove-referenced application Ser. No. 723,329, and involves depositing apattern of electrically and thermally conductive material on asubstrate, the pattern being in the form or configuration of asingle-wedge or double-wedge or "bow-tie" (tapering from a small centralpoint outwardly in opposite directions) but with each outer endterminating in or connected to two sets of contact points which makecontact with the terminals of a battery to be tested. The conductivematerial may be epoxy based silver, nickel or carbon. The testeradditionally includes an absorber or backing band or strip deposited onthe substrate, preferably on the same side of the substrate as theconductive pattern. A layer of a microencapsulated cholesteric liquidcrystal material is deposited on the opposite side of the substrate fromthe absorber layer. As used herein, the terms "cholesteric liquidcrystal", "liquid crystal" and "liquid crystal material" are usedinterchangeably throughout this description and refer to the same liquidcrystal materials disclosed and claimed herein. An indicator scale canalso be located along the length of the "bow-tie" shaped pattern, sincethe liquid crystal material changes color in a direction correspondingto the length of the conductive pattern, starting at a pointcorresponding to the central point of the pattern. The greater thedisplacement of the color change from the central point, the greater isthe current flow, which is proportional to the strength or condition ofthe battery. The dark or black backing material or backer makes thecolor change easily observable and may be derived from any dark paintsuch as a black latex or uv curing paint. Other paints or coatingmaterials are also suitable. A suitable protective coating may beoptionally applied over the "bow-tie" and conductive pattern except atthe terminal ends thereof, to protect it from wear and tear, and toensure correct placement of the tester contacts on the batteryterminals.

Cholesteric liquid crystals are chosen as the indicating materialsbecause of the brilliant iridescent colors they exhibit when exposed tochanges in temperature, pressure and electric fields. Cholesteric liquidcrystal materials suitable for use in the subject invention include butare not limited to cholesteryl chloride, cholesteryl oleyl carbonate,cholesteryl bromide, cholesteryl acetate, cholesteryl nanoate,cholesteryl oleate, cholesteryl caprylate, and the like. In addition,all the cholesteric liquid crystals disclosed and listed in U.S. Pat.Nos. 4,022,706 and 3,600,060 are incorporated herein by reference andmade a part hereof, as being suitable for use in the subject invention.

A determination of the amp-hours or the number of hours and ampsdischarged (or remaining battery life) for warranty purposes onelectrical appliances and the like, can be accomplished by accomplishedby the use of polyacetylene material deposited on top of a portion ofthe conductive patterns. This can be accomplished with a removablerecording label with pressure-sensitive backing, so that a permanentrecord is made. The polyacetylenic material responds optically turningdark with time and temperature. By placing an appropriately calibratedcurrent-time indicator comprising a quantity of polyacetylene on onehalf of one of the wedge-shaped sections of the liquid crystal materialof the tester, both the current condition of the battery and theamp-hours or battery life remaining (or consumed) can be readilydetermined. By a measurement of the optical change in the acetylenicmaterial at ambient temperature as compared to the optical change in theindicator during operation under testing conditions, background changeor "noise" can be biased. A measurement of the amp-hours or the usefullife of a battery or appliance remaining, can be useful in establishingor defending claims of warranties on electrical appliances, automotivebatteries and the like. It can also be used to periodically inspectequipment after 1 hours' use(?) By the use of a current-time indicatoremploying polyacetylenic materials, changes in ambient temperature mayalso be measured and compensated for changes in time and temperature.

Referring now to the drawings, FIG. 1 illustrates an embodiment of abow-tie configured pattern 10 of conductive material composed of a layerof granular metallic silver in an epoxy based coating material. Thebow-tie pattern consists of a small cross-sectional or central sectionalpoint 11 and a pair of outwardly tapering arm sections 12 whichterminate in curved ends 13 which, in turn, form an electrical contactwith the terminals of a dry cell battery as described hereinafter. Byway of example, the length `a` of pattern 10 is about four (4) inches,the length `b` being about two (2) inches and width `c` being about0.037 inch, the distance `d` being about 0.225 inch, and the radius `e`being about 0.112 inch. The configuration or pattern 10 is designed fortesting a battery having terminals on opposite ends thereof, asdescribed below.

FIGS. 2 and 3 illustrate an embodiment of the battery tester describedand claimed in copending application Ser. No. 723,329, and generallyindicated at 14, which utilizes two separate conductive materialpatterns 10 and 10' which are deposited on a transparent substrate orfilm 15 composed, for example, of transparent, high temperature stable,film or support of polyester (such as Dupont's mylar), polycarbonate,polyamide, polysufone, paper, preferably, fiber or nylon enforced,cellulose, laminates and the like. Other high-temperature stablepolymers are equally suitable.

The film 15 is preferably transparent so that the user can easily matchthe terminal ends or contacts 13 of the conductive pattern 10 with theterminals of the battery being tested as shown in FIG. 3. The film, forexample, may vary in thickness from about 0.001 inch, with a preferredthickness of about 0.002 to 0.005 inch. Film of a thickness less thanabout 0.001 inch would be too insubstantial to be operativesatisfactorily, for testing the condition of batteries, while a filmthicker than about 0.010 inch would result in longer response times(because the time required for the battery tester to reach thermalequilibrium would then be greater than 5-10 seconds) and consequent lossof the observed color change.

The conductive material forming patterns 10 and 10' is deposited on thefilm or substrate 15 by printing, coating, painting or otherconventional depositing techniques. This conductive material may beepoxy based silver, nickel or carbon and may be in the form of aconductive "ink". Silver is the most preferred conductor. Epoxy orurethane based silver, nickel or carbon and the like are the materialsof choice. The conductive material, preferably, should have a resistanceof about 0.1 to 0.020 ohms per square. The dimensions of the preferred"bow-tie" 10 of FIG. 2, for instance, are designed to give a patternthat will have a resistance of about 2-2.5 ohms. This is the optimumvalue given by the manufacturer (such as Union Carbide) of thecylindrical dry cell batteries in their manuals relating to their 1.5volt AAA, AA, C and D size batteries. The "bow-tie" pattern 10' of FIG.2 is designed to have a resistance of about 100 ohms, to test a 9 voltbattery. The tester tests the battery under a resistive load similar tothat in its normal operational uses. It was found that the testeroperated best over a range of 1-5 ohms with a preferred resistance ofabout 2.25 ohms for 1.5 v batteries. In the embodiment illustrated inFIG. 2, the ratio of the dimensions from the narrowest to the widesttaper of the silver conductive material is about 6 to 1 for the"bow-tie" pattern.

Referring again to FIG. 2, the conductive pattern 10' is designed fortesting a 9 volt transistor type battery (those having adjacentterminals or contacts) and includes a center point or section 11', apair of outwardly tapering arm sections 12', a pair of circuit paths orsections 16, connected to the outer ends of arms 12', which terminate incontacts or terminal ends 17 spaced so as to coincide with the distanceseparating the adjacent terminals on a conventional 9 volt transistortype battery (usually 50-150).

Layers 18 and 18' of a cholesteric liquid crystal material are depositedon the side of substrate 15 opposite to that on which the conductivelayer or patterns 10 and 10' are deposited and in alignment with theconductive patterns. A layer or band 19 of a black light absorber orbacking material or backer, such as a black latex paint, or black uvcuring paint is deposited on substrate 15 on the same side as theconductive patterns 10 and 10'. The absorber or backing layer or band 19does not extend the full length of arms 12 and 12' of the "bow-tie"pattern 10 and 10' so that the contact or terminal ends 13 extend beyondthe absorber layer 19, thereby enabling the user of the tester toobserve and match the contacts or terminals of the tester with theterminals of the battery being checked as illustrated in FIG. 3.Similarly, the width of the absorber or backer layer 19 does not extendto the circuit paths 16 or the terminal ends 17 of conductive pattern10' which enables the user to observe and match the contact betweenterminal ends 17 and the terminals of the battery being tested.Alternatively, the absorber or backer layer 19 can be deposited on thefilm or substrate 15, whereafter conductive patterns 10 and 10' aredeposited onto absorber layer 19 on the substrate adjacent the absorberlayer taking care that the terminal ends of the conductive patterns arenot covered or superimposed by the absorber layer. The liquid crystallayers 18 and 18' are then deposited on the opposite or other side ofthe substrate 15. Since liquid crystals diffracts only about 15% of anyincident light, the black light absorbing material facilitatesobservation and measurement of color changes in the liquid crystalmaterial against a dark background. Although the foregoing sequentialorder of depositing the various components is illustrated in theembodiment of FIG. 2, this order is not critical or necessary for theoperation of the tester. For instance, the conductive layer may bealternatively placed directly atop the absorber layer which is depositedon top of the liquid crystal layer, all on the same side of thesubstrate.

As shown in FIG. 2, substrate 15 is also provided with a plurality ofscale sections or segments located adjacent the edges of absorber orbacker layer 19, as indicated at 20 and 21 for conductive pattern 10 andat 22 and 23 for conductive pattern 10'. These scale segments may bedeposited directly onto substrate 15. The area of the patterns 10 and10' indicated by center scale segments 20 and 22 indicate a weak, "bad"or low battery, while the outer segments 21 and 23 indicate a strong,"good" or charged battery. For example, the center scale segments 20 and22 may be colored red, with the outer scale segments 21 and 23 beingcolored green to correspond to the conventional battery test colorcodes. While not illustrated in the figures, scale segments 20-23 may bemarked in voltage increments on an outwardly increasing scale from 0 atthe center point 11--11' to the full voltage on the outer portions ofarms 12 and 12'of the patterns 10 and 10' (i.e., 1.5 or 9.0, forexample). While the embodiments of the scale sections illustrated inFIG. 2 include spaces indicated at 24 and 25 between adjacent scalesections (between central section 20 or 22 and each of the outersections 21 or 23, for example) these spaces 24 and 25 may include aseparately colored portion (red and green striped or orange or red andblack striped, for example) to indicate that the battery is near weak or"replace soon" condition. Furthermore, the scale sections indicated inthe embodiment of FIG. 2 may be replaced with a continuous scale fromcenter points 11 and 11' to a selected outer point on arms 12 and 12'and be marked or calibrated from 0 volts at the center point to the fullvoltage, such as 1.5 or 9.0, at the outer point, and if desired, thescale may be colored gradually progressing from, for example, a brightred at the center point to a bright green at the outer point.

By way of example, the components of the battery tester illustrated inFIG. 2 may have the following dimensions: the transparent flexiblesubstrate 15 has a length of about 5 inches, width of about 2 inches,and thickness of about 0.005 inch. The absorber or backer layer or band19 has a thickness of about 0.0002 inch, a length of about 4 inches anda width of about 0.60 inch and, if desired, may be reduced to about 0.20inch. The liquid crystal layers 18 and 18' have a thickness of about0.002 inch, preferably about 0.001 inch. The dimensions of theconductive layer or pattern 10 is as described in a preceding sectionrelative to FIG. 1. The conductive layer or pattern 10' has an overalllength of about 4 inches, with a width at point 11' of about 0.010 inchand a width at the outer end of each arm 12' of 0.050 inch, with thecircuit paths 16 having a width of about 0.075 inch and an overalllength of about 2 inches (each circuit path 16 having an L-shapedconfiguration with the base or foot section having a length of about0.50 inch and the leg section having a length of about 1.5 inches) withcircuit paths 16 terminating in terminal ends 17 having about a 1/4 inchouter diameter. The terminal ends 17 are located about 1/2 inch apart.The thickness of the conductive patterns 10 and 10' is about 0.0002inch. The scale segment 20 is about 3/4 inch in length, with thesegments 21 being about 11/4 inch in length, while the scale segment 22is about 11/2 inches in length, with the segments 23 being about 1 inchin length. The conductive patterns 10 and 10' are separated by a sectionof the absorber or backer layer 19, as indicated at 24, which has awidth of about 0.10 inch. The purpose of reducing the length of theabsorber or backer layer 19 is to allow for a portion of the outersection of the conductive arms 12 to be exposed (i.e., not supported orcovered by the black absorber or backer material) for making electricalcontact. The conductive patterns 10 and 10' may be optionally covered byan insulating protective layer. Insulating protective material may beany conventional material used for such purposes, but is preferably a uvcuring ink.

While the dimensions indicated above are conveniently used in theembodiment of FIG. 2, other dimensions and shapes may be used for theconductive patterns. The two arms of the bow-tie configuration may beunequal in length and may be unsymmetrical.

An example of the operation of the battery tester such as the embodimentthereof illustrated in FIG. 2 is described below:

For a battery such as a conventional 1.5 volt type (AAA, AA, C and D forexample) with terminals located at opposite ends thereof, the flexiblesubstrate 15 is wrapped or curved around the battery such that theterminal ends 13 are placed in physical contact with the terminals of abattery 26, as shown in FIG. 3. The resulting current flow through theconductive pattern 10 places the battery 26 under an ideal resistiveload. The heating caused by the current flow results in color change inthe liquid crystal material 18 which shows up along arms 12 as describedabove. The strength or condition of battery 26 is readily determinedfrom the calibrated scale segments 20-21 which correspond to the colorchange along arms 12 of the conductive material.

The above description of the embodiment illustrated in FIG. 2, which isdescribed and claimed in copending application Ser. No. 723,329, hasbeen set forth in detail to provide a clear understanding of the basicfeatures of the tester and materials utilized in the constructionthereof. These basic features and materials are incorporated intovarious embodiments which illustrate the present invention. Theembodiments which illustrate the present invention constituteimprovements over and additions to the basic features of theabove-referenced copending application.

Referring now to FIG. 4, which illustrates an embodiment of the presentinvention, the tester shown has conductive patterns for testing 1.5 and9 volt batteries, similar to that of FIG. 2, but utilizes a pair of"bow-tie" shaped conductive patterns and a single pattern or layer ofliquid crystal material. The conductive patterns for the 9 volt and 1.5volt testing are superimposed on each other with an insulator materialtherebetween to separate them. This is better illustrated in theexploded view shown in FIG. 5.

The embodiment of the tester shown in FIGS. 4 and 5 is generallyindicated at 40 and is constructed such that the conductive patterns areon one side of a substrate and the absorber or backer layer and liquidcrystal material are located on the opposite side of the substrate, withthe voltage scales located adjacent the liquid crystal material. As moreclearly seen in FIG. 5, the tester 40 comprises a flexible, transparentsubstrate 41 having deposited on one side thereof a conductive pattern42 for a 9 volt battery, a silk screen printed insulative layer 43, anda conductive pattern 44 for a 1.5 volt battery. The "bow-tie" sectionsof patterns 42 and 44 are located so as to be coaxial with each other.An insulative layer or cover film 45 is deposited over the conductivepatterns 42 and 44 except at their respective contact points 46 and 47.Note that in FIG. 5, holes are shown in layers 43 and 45 which cooperatewith contact points 46 and 47 so that the insulation layer does notcover the contact points, thereby providing better electrical contactbetween the conductive patterns 42 and 44 and the terminals of anassociated battery to be tested. A appropriately calibrated scale 48 torepresent voltage or battery condition is deposited on or secured to aside of substrate 41, opposite the location of the "bow-tie" section ofthe conductive pattern 42. An absorber or black backer layer 49 isdeposited on the scale 48 so as to be coaxial (in alignment) with the"bow-tie" section of the conductive patterns, and a layer of liquidcrystal material 50 is deposited in turn on the backer or absorber layer49. A protective cover film 51 is deposited over the liquid crystalmaterial 50 and the scale 48. Scale 48 includes a 1.5 volt section,generally indicated at 52 and a 9 volt section generally indicated at53. By way of an example, the 1.5 volt section may include a centralweak, "bad" or low battery indicator segment 54 and two outer strong,"good" or charged battery indicator segments 55. Similarly, the 9 voltscale section 53 may include a central, weak battery indicator segment56 and the two outer strong battery indicator segments 57. The scale 48of tester 40 may be designed or configured as discussed in the sectiondescribing the embodiment of FIG. 2. Note that insulation layers 43 and45 have holes 58 which align with contact points 46, while insulatinglayer 45 is shown with holes 59 which align with contact points 47. Acomparison of the two embodiments represented in FIGS. 4 and 2respectively, will show that the difference between them lies in theelimination of one layer of liquid crystal material and superimposingthe conductive patterns on one another, thereby reducing the overallsize of the tester and associated savings in cost due to the utilizationof less material, while at the same time utilizing the liquid crystalmaterial more effectively.

While various techniques may be used to fabricate the embodiment of thebattery tester illustrated in FIGS. 4 and 5, the following is adescription of the fabrication process or method utilized to constructthe battery tester for experimental purposes for verifying theoperability of the invention. The method consists of the followingoperational steps:

(a) forming a substrate 41 of the desired dimensions from a piece ofmaterial such as a polyester, polyamide or polycarbonate which istransparent and flexible;

(b) depositing (printing or coating) a layer or pattern 42 of aconductive material on one side of substrate 41. This may beaccomplished using a template cut out to correspond to the desired shapeand dimensions of the conductive pattern 42;

(c) depositing a layer of electrically insulating material 43 over theconductive pattern 42 except at contact points 46. This may beaccomplished by silk screening or printing using various u.v. dielectricinks.

(d) depositing (printing or coating) a conductive layer or pattern 44 ofthe same or different conductive material as in step b above, onsubstrate 41 and over insulation layer 43 such that it is positioned oraligned with respect to the "bow-tie" section of pattern 42. The twodifferent conductive materials may be, for example, epoxy based silverfor one pattern and epoxy based nickel or carbon for the otherconductive pattern. A silk screen patterned to correspond to theconductive pattern 44 may be used for this purpose;

(e) depositing (printing or coating) a scale 48 for each of the patterns42 and 44 on the opposite side of substrate 41 such that the centerthereof is aligned with the "bow-tie" section of conductive patterns 42and 44. Silk screens with appropriate cut out patterns for the scalesegments may be used;

(f) depositing a layer or band 49 of a black backer or absorber materialsuch as black latex or uv curing paint, of a desired length and width onthe other or opposite side of substrate 41 so as to extend over andalign with the central section of scale 48 and the "bow-tie" section ofpatterns 42 and 44. This may be done using a template cut out tocorrespond to the desired shape and dimensions or may be silk screen oroff-set printed on the substrate material;

(g) depositing (printing or coating) on the substrate 41 and over backerlayer 49, a layer or coating 50 of a microencapsulated liquid crystalmaterial. This may be accomplished using a template cut out to therequired or desired pattern or dimensions or may be silk screen or offset printed on the substrate; and

(h) depositing (printing or coating) protective nonconductive films 45and 51 over the areas of the conductive patterns 44 except at contactpoints 47 and over the liquid crystal layer 50, using materials such asuv curing paints. This provides environmental and insulative protectionfor the patterns 44. The protective layer may be omitted, if desired.

In fabricating the battery tester of FIG. 4, the above process may bemodified such that the conductive patterns 42 and 44 are printed,painted or coated over a black absorber or backer layer located on thesame side of substrate 41 as the patterns, but such that the terminalends extend beyond the absorber or backer layer. In addition, the widthof the absorber layer 49 may be increased from that shown in FIG. 5 suchthat an outer portion of conductive pattern 42 contacting the contactpoints 46 is exposed (not covered or backed by absorber 49) so as toexpose less of the silver conductive material. However, it is preferredthat the black band or absorber layer 49 be made narrow as shown in FIG.5, to delineate a sharp vertical or horizontal line as the liquidcrystal material changes color when it is heated by the conductivepattern as the current passes therethrough.

Although the preferred method of fabrication shows the foregoingsequence of steps, such sequence is neither crucial nor necessary forthe operation or practice of the present invention. Alternatively, theliquid crystal, absorber, conductive patterns and the protective coatingmay all be located on the same side of the substrate. For instance, alayer of the liquid crystal material is initially deposited on thesubstrate, followed by a layer of the absorber. The conductive patternsare then deposited on top of the absorber, but with an insulative layerbetween the patterns and then coated with the insulating protectivecoating.

The operation of the battery tester such as the embodiment thereofillustrated in FIG. 4 is carried out by positioning contact points 47 onthe terminals of a battery, in the same manner as illustrated in FIG. 3for a 1.5 volt battery. For testing a 9 volt battery, the batteryterminals would be placed in contact with contact points 46.

Referring now to the embodiment illustrated in FIG. 6, which, forsimplicity, illustrates only a 1.5 volt conductive pattern, but a 9 voltpattern may be added as shown in either FIG. 2 or FIG. 4, with theadditional amp-hour indicator feature being included. The amp-hourindicator is composed of a quantity of polyacetylenic materialpositioned on top of a section of the liquid crystal material, whichoptically turns dark with time and temperature. This indicates amp-hrsor the number of hours and amperes discharged (for determining theremaining battery life). It can also be used for warranty purposes onsmall electricals, electrical appliances and the like.

Referring now to FIG. 6, the battery tester generally indicated at 60comprises a substrate 61 on which is deposited a conductive patternhaving contact points 62. The conductive pattern includes a "bow-tie"shaped section over which is deposited a quantity of liquid crystalmaterial 63, with a scale or voltage indicator 64 positioned adjacentthe liquid crystal material 63. The scale 64 may include a centersegment 65 and a pair of outer segments 66 which function as describedabove with respect to segments 54 and 55 of the FIG. 4 embodiment. Also,while not shown, the embodiment of FIG. 6 may utilize a layer ofabsorber or backer material as described above. Positioned on one wedgeor section of the "bow-tie", commencing at the center thereof, is alayer of polyacetylenic material 67, forming an amp-hour indicator.However, if desired, the material 67 may extend along the centersegments or sections of both wedges of the "bow-tie". The polyacetylenicmaterial may also be disposed as a detachable layer.

By way of example, the material 67 may be composed of acetylenicpolymethane, polydiacetylene, or polydiacetylenic urethanes, and extendsalong a length of polydiacetylenes with the "bow-tie", for example,having the dimensions described in the embodiment represented by FIG. 1.

In operation, the embodiment of FIG. 6, with the contact points 62 incontact with the terminals of a 1.5 volt battery, such as that shown inFIG. 3, the liquid crystal material 63 changes color proportional to thecondition of the battery, as described earlier. The polyacetylenicmaterial turns dark as a function of time with the passage of current.The materials used for the various components 61, 62, 63 and 64 in FIG.6 may be the same as those described for the embodiment of FIG. 4.

The embodiments illustrated in FIGS. 7 and 7A incorporate a plurality ofvoltage taps or battery contact points which enable the same tester tobe used on batteries of different voltages, such as the 1.5 volt batteryas described above, or 4.5, 6 and 9 volt batteries, for example. whilenot shown in the figure, it is within the scope of this invention toutilize a substrate configuration which has a folded or accordion(expandable or contractable) or hand-fan type construction for use withmultiple batteries with the same or different voltages.

Referring first to FIG. 7, a tester using the plural contact point ortap arrangement is generally indicated at 70 and includes a substrate 71on which is deposited a conductive pattern composed of segments orsections generally indicated at 72, 73, and 74 with respective contactpoints or voltage taps at 75, 76 and 77. A pair of layers of liquidcrystal material 78 and 79 are deposited onto substrate 71 adjacentconductive pattern sections or segments 72 and 73. A backer or absorberlayer 80 is deposited so as to be between substrate 71 and both of theconductive patterns and the liquid crystal material, and functions asdescribed above. Conductive pattern segments 72 and 74 are in thegeneral form of an upside-down L-configuration, while pattern segment 73is in the general shape or form of an upside-down U configuration. Thepattern segments 72 and 74 each basically consist of a base section 81and an arm or leg section 82, while pattern segment 73 basicallyconsists of a base section 83 and a pair of arm or leg sections 84. Notethat the arm sections 82 and 84 form an angle with respect to the basesection which is greater than 90°. Each of arm or leg sections 82 and 84taper from their base section 81 and 83 to a point of interconnection at85 so as to form a continuous conductive pattern from contact point ortap 77. The layer of liquid crystal material 78 is located adjacent armor leg section 82 of conductive pattern segment 72, while liquid crystalmaterial layer 79 is located adjacent arm or leg section 84 ofconductive pattern segment 73. While not shown, a scale or voltageindicator as described earlier, may be located adjacent the liquidcrystal material layers 78 and 79.

In the operation of the tester of FIG. 7, the terminals of a battery tobe tested are placed in contact with two of the three contact points 75,76 and 77, depending on the voltage of the battery being tested. As thecurrent flows through the conductive pattern, it causes heating andchange in color of the liquid crystal material proportional to the flowof current which is, in turn, proportional to the charge state orcondition of the battery.

With the battery terminals being in contact with contact points 75 and77, for example, and considering the battery to be a 6 volt type, thevoltage may be easily read on the appropriately calibrated scale.

With the battery terminals being in contact with contact points 75 and76, or with contact points 75 and 77, and considering the battery to bea 4.5 volt type, a voltage reading may be obtained from theappropriately calibrated scale.

Fabrication of the embodiment of FIG. 7 may be carried out in a manneras described earlier. The primary difference here is in theconfiguration of the conductive pattern and in the location of theliquid crystal material adjacent the conductive pattern rather thanbeing deposited on top of the conductive pattern.

By way of example, the conductive pattern segments 72, 73 and 74 mayhave the following dimensions. Segments 72 and 74 have a base section 81with a length of 43/4", including contact points 75 and 76 and with awidth of 0.200", with contact points having a radius of about 0.250'.The arm or leg sections 82 of segments 72 and 74 have a length of 13/4",and tapering from a thickness of 0.150" at the base 81 to 0.030" atinterconnecting point 85. The angle of the arm or leg sections 82 withrespect to the base section 81 is 0.88. Conductive pattern, the backeror absorber layer, and the liquid crystals may be composed of the samematerials as described earlier in connection with the embodiments ofFIGS. 2 and 4. Additionally, a protective film or coating may be appliedover at least the conductive pattern except over the contact points, aspreviously described.

FIG. 7A illustrates another multiple voltage tap arrangement but differsfrom that illustrated in FIG. 7 in that the liquid crystal material isdeposited on the "bow-tie" section of the conductive pattern, ratherthan adjacent the conductive pattern, and each additional voltage tap isconnected to the "bow-tie" by a conductive path. An indicator scale isnot shown but may be positioned as illustrated in FIG. 6, but designedto indicate the voltage when different voltage settings or taps orcontact points are used.

As shown in FIG. 7A, the tester, generally indicated at 90, basicallycomprises a substrate 91, a conductive pattern generally indicated at 92and a layer of liquid crystal material 93 located over the "bow-tie"section of the conductive pattern, as in the embodiment of FIG. 6. Alayer of backer or absorber material, not shown, can be depositedbeneath the liquid crystal material as previously described. The"bow-tie" section of the conductive pattern 92 terminates at the otherends thereof in contact points 94 and 95. A plurality of contact points96, 97 98 and 99 are spaced along the length of the pattern 92 and areconnected to the "bow-tie" by respective conductive paths 96', 97',98'and 99'. Each of the contact points are designed and positioned suchthat when a battery is connected between a set of contact points, it istested under a resistive load similar to that in its normal operationaluses. As previously described, a protective layer or film may be appliedover the conductive pattern, except over the contact points, and overthe liquid crystal material, if desired.

By way of example, to test a 1.5-volt battery, contact points 97 and 98would be used. For a 4.5-volt battery, contact points 96 and 99 would beused. For a 6-volt battery, contact points 95 and 94 would be employed.

The embodiment of FIG. 7A may be fabricated using the techniques andmaterials previously described.

While the embodiments of FIG. 4, 6 and 7A use conductive patterns,including a "bow-tie" shaped section, other conductive patterns orshapes may be used provided that the correct resistance ratio ismaintained along the length of the pattern. Although two conductivepatterns are deposited on the same substrate as illustrated in FIG. 4for ease and convenience of use, the subject tester is not limited tosuch a configuration. For instance, where only a tester for the 9 volttype battery with two adjacent terminals is desired, the substrate onwhich the conductive pattern is deposited need not be flexible and/ortransparent so long as transparent windows or window sections areprovided in the substrate to correspond with the contact terminal endsections of the conductive material or pattern of the tester so that theuser can easily match the tester terminals with the battery terminals.Only one conductive pattern, one for the 1.5 volt battery type and onefor the 9 volt battery type, may be deposited each on a separate pieceof substrate. Two conductive patterns for the same general type ofbatteries i.e., with terminals located at opposite ends thereof, butwith different voltage capacities, may also be deposited on the samesubstrate piece, for example, a 1.5 volt and a 4.5 volt battery eachwith terminals located at opposite ends thereof as illustrated in FIG.6. Two dissimilar conductive patterns or two dissimilar materials withdifferent resistivities, such as silver and nickel, or silver and carbonor carbon and nickel, may also be utilized for different resistive loadsand different voltages other than 1.5 and 9.

It has thus been shown that the present invention provides a device ofsimple construction which yet provides an effective, inexpensive,completely portable and simple means for testing the condition orvoltage output of small portable batteries such as for example dry cellbatteries. The invention, thus, fills the need which has existed in theart of battery testing devices.

The foregoing description of various embodiments of the invention havebeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and obviously many modifications and variations are possiblein light of the above teaching. The embodiments were chosen anddescribed in order to best explain the principles of the invention andits practical application to thereby enable others skilled in the art tobest utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto.

I claim:
 1. A battery tester which utilizes liquid crystal material thatchanges color proportional to the current produced by a battery beingtested, said tester comprising:a substrate constructed of flexiblematerial; at least one pattern of electrically conductive materialhaving terminal end sections located on said substrate; and at least onelayer of a cholesteric liquid crystal material located on said substrateand in alignment with and extending along a portion of said conductivematerial pattern; said substrate being constructed of material ofsufficient flexibility to enable said terminal end sections of saidelectrically conductive material to be placed in contact with theterminals of an associated battery; scale means having calibrationmarkings thereon for indicating the strength of an associated battery;and whereby contact of said terminal end sections with terminals of anassociated battery to be tested causes a current to flow through saidcondutive material which causes portions of said conductive material toheat, the heat being transferred to said liquid crystal material causingsaid liquid crystal material to change color proportional to the currentflowing through said conductive material.
 2. The battery tester of claim1, further including a layer of absorber material located on a portionof said substrate and underneath said liquid crystal material.
 3. Thebattery tester of claim 1, further including a scale located on saidsubstrate and extending substantially parallel to at least portions ofsaid pattern.
 4. The battery tester of claim 1, further including a pairof different patterns of electrically conductive material superimposedon one another and separated from one another by a layer of insulativematerial.
 5. The battery tester of claim 4, wherein said patterns ofelectrically conductive material are located on one side of saidsubstrate, and wherein said liquid crystal material is located on anopposite side of said substrate.
 6. The battery tester of claim 5,wherein said substrate is constructed of transparent material.
 7. Thebattery tester of claim 5, additionally including a layer of absorbermaterial located between said substrate and said liquid crystalmaterial.
 8. The battery tester of claim 5, additionally including ascale located on said substrate adjacent to and extending along at leasta portion of said layer of liquid crystal material.
 9. The batterytester of claim 5, additionally including a protective coating over atleast said patterns of conductive material except at the location ofsaid terminal end sections of said patterns.
 10. The battery tester ofclaim 1, additionally including means for determining amp-hours of anassociated battery to be tested, said means being located along asection of said liquid crystal material.
 11. The battery tester of claim10, wherein said means includes a quantity of polyacetylenic material.12. The battery tester of claim 1, wherein said pattern of electricallyconductive material includes at least one contact point locatedintermediate said terminal end sections thereof.
 13. The battery testerof claim 12, wherein said pattern of conductive material includes atleast a pair of generally L-shaped sections at least one generallyU-shaped section, each of said L-shaped sections having a base portionand an arm portion, said U-shaped section having a base portion and apair of arm portions, said U-shaped section being positionedintermediate said L-shaped sections and having each of said arm portionsconnected at an outer end thereof to an outer end of an arm portion ofsaid L-shaped section, said terminal end sections of said pattern ofconductive material being located in said base portions of said L-shapedsection, said contact point being located in said base portion of saidU-shaped section.
 14. The battery tester of claim 13, wherein said layerof liquid crystal material is located along one of said arm portions ofsaid pattern of conductive material.
 15. The battery tester of claim 13,wherein a layer of liquid crystal material is located adjacent an armportion of one of said L-shaped sections and another layer of liquidcrystal material is located adjacent an arm portion of said U-shapedsection.
 16. The battery tester of claim 13, wherein said arm portionsof said L-shaped sections and said U-shaped sections are tapered in adirection outwardly from said base portions thereof.
 17. The batterytester of claim 12, wherein said pattern of electrically conductivematerial includes a plurality of contact points located in spacedrelation with one another and intermediate said terminal end sections ofsaid conductive material.
 18. The battery tester of claim 12, whereinsaid pattern of electrically conductive material includes a "bow-tie"configured section, and wherein said plurality of contact points arelocated along said "bow-tie" configured section and connected thereto byconductive paths.